Monoclonal and polyclonal antibodies to choline acetyl transferase (ChAT) will be used to immunoisolate messenger RNA which codes for the ChAT enzyme. Human placental tissue, which has been shown to be a rich source of ChAT, will be used as a source of polysomes for this effort. Human tissue (obtained by autopsies of Alzheimer's disease patients as well as controls who died of other causes) from the basal forebrain regions will be utilized to isolated mRNA so that disease specific and region specific libraries of complementary DNA can be created. These libraries will be used to screen for cDNA clones whose presence or absence is associated with Alzheimer's disease. The ChAT clones and the other Alzheimer related clones will be used to study the growth and development of brain cells in culture via in situ hybridization and RNA quantitation.